body {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #fff;
}
.container {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: 50px;
  color: #fff;
  font-size: 60px;
}

.btn {
  padding: 6px 20px;
  background-color: #2179f5;
  border-radius: 6px;
}
.circle-btn {
  padding: 6px 20px;
  background-size: 70% 70%;
  background-image: 
    radial-gradient( circle at 100% 100%, transparent 0, 
      transparent 12px, #2179f5 13px),
    radial-gradient( circle at 0 0, transparent 0,
      transparent 12px, #2179f5 13px),
    radial-gradient( circle at 100% 0, transparent 0,
      transparent 12px, #2179f5 13px),
    radial-gradient( circle at 0 100%, transparent 0,
      transparent 12px, #2179f5 13px);
  background-repeat: no-repeat;
  background-position: right bottom, left top, right top, left bottom;
}
.box-shadow {
  box-shadow: 0 4px 20px #ccc;
}
.drop-shadow {
  filter: drop-shadow(0 4px 20px #ccc);
}

